C++ :: Spaceship Game - Creating Gravity For Each Object Depending On Mass

I've been having trouble working on this physics engine of mine. Right now I'm having trouble adding gravity.

The game is a spaceship--which you control--flying around in space with asteroids and eventually the ability to shoot bullets. There should be a wrap on the edges of the screen and gravity for each object depending on their mass.

I'm creating a forceX and forceY for each force put onto each object, and then computing that force into a velX and velY which will determine the direction of each object and at which speed.

Where my problem arises:

Code:
//add gravity pulls to forces
for(int i = 0; i <= pushCount; i++) //add gravity pulls for each object {
for(int u = 0 ; u <= pushCount; u++) //each object should add a force for every other object {
if(i != u) {
switch(id[i])

[Code] ....